: Imagine that you're Foehammer. A call comes in from a very dangerous zone...
: "Hey, can you pick us up? We just set off the Autumn's core so we
: could blow it up, and we'd like to get out of here."

True. That was the one at the top of my 'reasonable explanations' list. For a while...

Then I said to myself:

"She had plenty of time to explain earlier. So why didn't she?"

: Who says they haven't? Either Cortana has been unable to pick up an evac
: signal, and/or the vast majority of human soldiers have already been
: Flooded. Remember, the Covenant at least have energy shields to delay
: their infection... the humans are much more vulnerable, even with their
: shotguns.

It's probable. Although I would have expected Bungie to have slung something in like Foe Hammer responding with:

"Cortana! Chief! Damn, I thought I was the only one left!"

...when first contacted, just to re-enforce the notion. But, again, it's just a guess...

: Apparently, a lifeboat did remain, and would have been sufficient. If you
: look at the storyboards on the official site, the original plan was for
: the final Warthog run to end at a lifeboat bay and have the Chief climb on
: board, blast one last Flood, and take off. No Longsword involved.

But would Foe Hammer been warned in that scenario? Again, we don't know. That was my problem with it. It just bugs me that there was no attempt made to tell anyone else. I would have expected that in the circustances.